fix(Button): 修復 breakpoints.map is not a function 問題

原因出在 styled-system@^5.1.4 底下的 @styled-system/css/dist/index.esm.js 第 115 與 116 行：

```js
var breakpoints = get(theme, 'breakpoints', defaultBreakpoints);
var mediaQueries = [null].concat(breakpoints.map(function (n) {
```

這裡的 `theme.breakpoints` default 本來應該是 array，但因為 2B 剛好也有 `theme.breakpoints`，而且類型是 object，加上 theme override [1] 機制在 [email protected] 又壞掉！

所以兩個問題加起來，導致 `breakpoints.map is not a function`。

解決方法：

1. 避免 Button 的 theme 被 override [1]
2. 升級 [email protected] 修復 theme override bug [2][3]

- [1] https://styled-components.com/docs/advanced#the-theme-prop
- [2] styled-components/styled-components#294
- [3] styled-components/styled-components@14c1c29

Ref hahow/hahow-for-business#724

package.json

@@ -36,7 +36,7 @@
   },
   "peerDependencies": {
     "react": "16.x",
-    "styled-components": ">= 4"
+    "styled-components": ">= 5"
   },
   "devDependencies": {
     "@percy/storybook": "^3.2.0",
@@ -67,7 +67,7 @@
     "nwb": "0.23.x",
     "react": "^16.12.0",
     "react-dom": "^16.12.0",
-    "styled-components": "^4.4.1"
+    "styled-components": "^5.0.0"
   },
   "author": "",
   "homepage": "",

src/components/Button/Button.jsx

@@ -37,26 +37,25 @@ const Button = ({
   // 以下為另外處理的 props
   children, icon, iconPos, testId,
 }) => (
-  <ThemeProvider theme={theme}>
-    <StyledButton
-      block={block}
-      brand={brand}
-      className={className}
-      data-test-id={testId}
-      disabled={disabled}
-      href={href}
-      htmlType={htmlType}
-      loading={loading}
-      onClick={onClick}
-      size={size}
-      target={target}
-      type={type}
-    >
-      {icon && iconPos === 'left' && <Icon type={icon} />}
-      {children}
-      {icon && iconPos === 'right' && <Icon type={icon} />}
-    </StyledButton>
-  </ThemeProvider>
+  <StyledButton
+    block={block}
+    brand={brand}
+    className={className}
+    data-test-id={testId}
+    disabled={disabled}
+    href={href}
+    htmlType={htmlType}
+    loading={loading}
+    onClick={onClick}
+    size={size}
+    target={target}
+    theme={theme}
+    type={type}
+  >
+    {icon && iconPos === 'left' && <Icon type={icon} />}
+    {children}
+    {icon && iconPos === 'right' && <Icon type={icon} />}
+  </StyledButton>
 );
 
 Button.propTypes = {